Most extracorporeal lithotripters utilize x-rays and/or ultrasound devices for aiming the reflector of the lithotripter to place the second focus point directly on the kidney stone that is to be destroyed. In our copending application Ser. No. 07/856,373, filed Mar. 23, 1992 with the title ULTRASOUND TRANSDUCER SHIELDING now U.S. Pat. No. 5,240,002) we have disclosed an extracorporeal lithotripter in which aiming is accomplished by way an ultrasound transducer mounted within the reflector in fixed relation thereto. We have provided a heavy metallic shield surrounding the transducer that protects the transducer from direct shockwaves generated by the spark gap in the reflector. Further study has indicated that there may be some shockwaves reflected by the interface between the reflector diaphragm and the human body which could bounce up against the ultrasound transducer to cause damage thereto.